<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>Ajax应用</title>
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
  </head>
  <script type="text/javascript">
  var xmlHttp;
  	function createHttpRequest(){
  		if(window.ActiveXObject){
        	xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
        }
        else if(window.XMLHttpRequest){
        	xmlHttp=new XMLHttpRequest();
        }
     }
     function beginCheck(){
     	var xh=document.all.xh.value;
     	if(xh==""){
     		alert("对不起，请输入注册学号");
     		return;
     	}
     createHttpRequest();
     xmlHttp.onreadystatechange=processor;
     xmlHttp.open("get","CheckUser?xh="+xh);
     xmlHttp.send(null);
     }
     function processor(){
     	var responseContext;
     	if(xmlHttp.readyState==4){
     		if(xmlHttp.status==200){
     			responseContext=xmlHttp.responseText;
     			if(responseContext.indexOf("true")!=-1){
     				alert("恭喜你，该学号有效");
     			}else{
     				alert("对不起，该学号已经被注册");
     			}
     		}
     	}
     }						
  </script>
  <body>
    <form action="">
    	学号：
    	<input type="text" name="xh" onchange="beginCheck()"/>
    	口令：
    	<input type="password" name="kl"/>
    	<input type="submit" value="注册"/>
    </form>
  </body>
</html>
